1. Field of the Invention
The present invention relates to toothbrushes, and more particularly, to toothbrushes which exhibit improved tooth and gum cleaning characteristics. These toothbrushes include toothbrush bristles with a particular geometric cross-sectional area.
2. Description of the Prior Art
Early toothbrushes were fabricated from readily available natural materials. The bristles employed in these brushes ultimately were fabricated of animal bristles, particularly those of the wild boar. This was due to their good flexibility, their liquid retention characteristics and even their appearance. These natural bristles were, of course, round in cross-sectional area.
As synthetic materials, such as various polymeric organic materials, became available, attempts were made to develop synthetic bristle materials which closely resembled the natural bristle materials which had gained widespread acceptance in the marketplace. See, for example British Patent Application 1,076,967 to Societe Rhodiaceta, published Jul. 26, 1967. Typically, these synthetic bristles were produced by extruding the molten synthetic polymer through a round orifice.
As those skilled in the art gain familiarity with the synthetic extrusion technology, they began experimenting with new cross-sectional geometric shapes in an effort to enhance the performance of brushes in general. For example, U.S. Pat. No. 2,317,485, to Rider, issued Apr. 27, 1943 relates to a toothbrush with improved cleaning ability due to the shape and nature of the bristles. The Rider invention stems from the observation that circular cross-sectional bristles do not pack into tuft holes well and that other regular geometric shapes, e.g., triangles, squares, pentagons, hexagons, heptagons, and octagons, allow one to pack more bristles into a given tuft hole. Also, U.S. Pat. No. 2,876,477 to Stewart, issued Mar. 10, 1959 relates to another toothbrush which utilizes polygons of regular cross-sections, e.g. squares, pentagons, hexagons, heptagons, octagons, nonagons, etc. Contrary to Rider, Stewart seeks to maximize interstacial spacing by providing these polygons with a concave contour on each side. Still further, U.S. Pat. No. 3,032,230 to Poppelman, issued Feb. 7, 1967 relates to a toothbrush wherein the bristles, head and handle are molded into a single unit. Poppelman indicates that the preferred bristle cross-section should be of a polygon with at least two acute angles, e.g. triangle, rhombus, and a four-pointed star pattern. Poppelman speculates that those shapes impart a scraping effect on the teeth. And yet further, U.S. Pat. No. 3,344,457 to Grobert, issued Oct. 3, 1967 discloses a paint brush filament with improved paint pickup and release characteristics. Grobert's synthetic filaments are tapered and have a cruciform ("+") cross-sectional area.
With regard to toothbrush bristles with a rectangular cross-sectional area, which are the focus of the present invention, U.S. Pat. No. 3,214,777 to Kutik, issued Mar. 17, 1964, discloses a molded plastic toothbrush wherein the bristles have a rectangular cross-sectional area and the bristles of each adjacent row are slightly staggered. Kutik recognizes that rectangular bristles having flat sides and relatively thin edges permit a free flexing of the bristles transversely while the flexing of the bristles longitudinally is retarded due to the cross-sectional shape of the bristles. Kutik goes on to say that this allows you to have a soft yielding motion in the up and down brushing orientation and firm brushing motion in the in and out orientation (see Col. 1, lines 11-28 and Col. 2, lines 16-23). Kutik does not employ standard bristle material which is typically packed into tuft holes. In fact, Kutik utilizes a molded bristle configuration which employs a plurality of very thin comb-like laminations which are bolted together to form the brush. (see particularly FIG. 6 and 7). In fact, Kutik is silent as to the use of conventional bristle filament materials.
Recently, rectangular bristle filaments of the traditional type, which are affixed to a toothbrush head in tuft bundles, have become available. DuPont Polymers, Wilmington, Del. has recently begun marketing TYNEX.RTM. rectangular toothbrush filaments. DuPont indicates that as the bristle anchoring staple is inserted into the tuft hole, most of the bristles orient themselves in a particular directional orientation. DuPont further indicates that brushes fabricated in this manner are stiffer in the direction of the handle and softer from side to side.
These prior art references, taken alone or in combination, fail to teach, imply or suggest the use of more than one directional orientation of rectangular bristles in a toothbrush head. Furthermore, these references fail to appreciate the significant improvement in tooth and gum cleaning which can be realized when at least two directional orientations of rectangular bristles are employed in a toothbrush. It is an object of the present invention to overcome the shortcomings of the prior art and to provide a toothbrush which exhibits improved cleaning performance.
These and other objectives will become evident from the following: